"On the Day [some] faces will turn white..."

On the Day [some] faces will turn white and [some] faces will turn black. As for those whose faces turn black, [to them it will be said], "Did you disbelieve [i.e., reject faith] after your belief? Then taste the punishment for what you used to reject." But as for those whose faces turn white, [they will be] within the mercy of Allah. They will abide therein eternally.